This is a randomized, dose finding study of Rebif for the treatment of patients with chronic hepatitis C resistant to interferon alpha. Subjects will be randomized to receive one of four treatment regimens of Rebif (interferon beta-1a) for 48 wseeks: 12 MU TIW, 12 MU daily, 24 MU TIW or 24 MU daily. Follow-up will be for an additional 24 weeks.